One of the obstacles limiting the application of electrospun scaffolds for tissue engineering is the nanoscale pores that inhibit cell infiltration. In this article, we describe a technique that uses ice crystals as templates to fabricate cryogenic electrospun scaffolds (CES) with large three-dimensional and interconnected pores using poly(D,L-lactide) (PLA). Manipulating the humidity of the electrospinning environment the pore sizes are controlled. We are able to achieve pore sizes ranging from 900 +/- 100 microm(2) to 5000 +/- 2000 microm(2) depending on the relative humidity used. Our results show that cells infiltrated the CES up to 50 microm in thickness in vitro under static culture conditions whereas cells did not infiltrate the conventional electrospun scaffolds. In vivo studies demonstrated improved cell infiltration and vascularization in the CES compared with conventionally prepared electrospun scaffolds. In gaining control of the pore characteristics, we can then design CES that are optimized for specific tissue engineering applications.

This study was undertaken to review the outcome of open trigger digit release of 483 digits in 373 consecutive patients over a 1 year period. Parameters were obtained from case records. The patients were followed up for a minimum of 6 months postoperatively. The most commonly affected digits were the ring (42%) and middle (26%) fingers. Based on the classification by Wolfe [Tenosynovitis. In: Green DP (Ed). Operative hand surgery, 5th Edn. New York, Churchill Livingstone, 2005: 2137-2159], Grade II (51%) and III (33%) trigger digits accounted for majority of affected digits. Non-operative treatment was the first line modality for 82% of the patients. Primary surgical release (18% of patients) was performed for patients who had refractory conditions, grade IV triggering and those who requested this treatment. The overall complication rate was 1%. These included superficial wound dehiscence, extension lag and postoperative residual stiffness. There were no recurrences of triggering. Steroid injection is recommended as the first line treatment. Surgical release is recommended for refractory and severe triggering.

Cryogenic electrospinning has previously been demonstrated for controlling the pore sizes of electrospun scaffolds, which has been impossible with traditional electrospinning processes. This article describes the application of the cryogenic technique to fabricate a bilayered electrospun poly(D,L-lactide) scaffold (BLES) in a single uninterrupted process. The resulting BLES consisted of a traditional electrospun (ES) fibrous layer with a dense pore area of 17 +/- 3 microm(2) adjacent to a cryogenic electrospun layer (CES) with a pore area of 3300 +/- 500 microm(2). The significance of this bilayered scaffold was to mimic the anatomical structure of tissues with dense basement membrane followed by loose and highly porous connective tissue such as skin and blood vessels. Cell infiltration in the BLES was compared in vitro and in vivo. Both studies suggested the CES supported high cell infiltration, whereas the ES could serve as a physical barrier to prevent cell infiltration across the CES-ES boundary because of its size exclusion. The bilayered structure produced by this technique suggests a great potential for engineering tissues with similar architectures.

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